Last week, a fire on a Japan Airlines Boeing 787 Dreamliner parked in Boston prompted American regulators to launch a comprehensive review of the new jet program. But they maintained the plane was safe and allowed it to keep flying during their unusual if not unprecendented re-examination.

That changed Wednesday after pilots on an All Nippon Airways 787 had to make an emergency landing after another smoky battery malfunction. Before the day was over, the FAA had grounded Boeing’s technologically advanced jetliner, declaring that it won’t fly again until the onboard batteries are proven to be safe.

“Before further flight, operators of U.S.-registered Boeing 787 aircraft must demonstrate to the Federal Aviation Administration ... that the batteries are safe and in compliance,” the U.S. agency said in a statement accompanying its emergency airworthiness directive.